Fluorescent proteins, such as green fluorescent protein (GFP), are indispensable as a tool for visualizing cells, tissue, biological individuals, and so on.
Most of fluorescent proteins have been isolated from invertebrates such as coral, sea anemones, and arthropods. However, for example, Non Patent Literatures 1 and 2 and Patent Literatures 1 and 2 report that a vertebrate, Japanese eel (Anguilla japonica), has a fluorescent protein.